I just ordered a new SSD, and so I am planning to reinstall my Debian system. I have an Intel Core 2 Quad CPU (Q9450). Does it make sense to install the 64bit version (I have just 4GB of RAM, plus 1GB on the graphics card if it makes any difference, but I am considering increasing this amount). Which architecture should I choose?

Also I am using the proprietary nvidia drivers, do they work at all and are they stable on the 64 bit systems?